Liquid crystal display device

ABSTRACT

To provide a liquid crystal display device in which it is possible, with a simple configuration, to avoid a bright spot defect caused by a polishing flaw, called a dimple, formed in a surface of an observer side substrate of a liquid crystal display panel. 
     A liquid crystal display device includes:
         a liquid crystal display panel having a first substrate, a second substrate disposed on an observer side of the first substrate, and a liquid crystal layer sandwiched between the first substrate and the second substrate, and   a transparent cover affixed by means of a first bonding member to a surface of the liquid crystal display panel on the observer side, wherein   the transparent cover has an optical member affixed by means of a second bonding member to a surface of the transparent cover facing the second substrate,   the second substrate has a chemically polished surface on the observer side,   the first bonding member, as well as making direct contact with both the polished surface of the second substrate and the optical member, covers all of a surface portion of the second substrate facing a display area, and   the first bonding member is 30 to 200 μm in thickness, while the second bonding member is 10 to 25 μm in thickness.

The present application claims priority from Japanese applicationJP2008-10047 filed on Jan. 21, 2008, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a liquid crystal display device, and inparticular relates to a liquid crystal display device to a surface of aliquid crystal display panel of which a transparent cover is affixed bymeans of an adhesive.

2. Related Art

For example, as a liquid crystal display device for a portabletelephone, one is known in which a protective cover (a transparentcover) made of, for example, an acryl resin, or the like, is disposed ona surface of its liquid crystal display panel, and they are affixedtogether with an adhesive.

A liquid crystal display device is also known which, in the event thatan air layer exists between a protective cover and a liquid crystaldisplay panel, as an unnecessary interface reflection occurs in aninterface with the air layer, causing a reduction in a display contrast,is configured having the protective cover affixed to the liquid crystaldisplay panel by means of the adhesive (which has a refractive indexclose to that of the transparent cover) in advance.

Herein, the liquid crystal display panel is configured having a pair ofsubstrates made of, for example, glass bonded together via a sealmaterial, and a liquid crystal layer sandwiched between the pair ofsubstrates. Then, a polarizing plate is disposed, by means of anadhesive, on a surface of each substrate opposite to the liquid crystallayer.

For this reason, the protective cover is configured affixed to a topsurface of the polarizing plate disposed on an observer side of theliquid crystal display panel.

A liquid crystal display device of this kind of configuration isdisclosed in JP-A-2007-178758. Also, as patent documents relating to theinvention, apart from JP-A-2007-178758, there are JP-A-2001-42301,JP-A-4-326419, JP-A-2006-221187 and JP-A-2007-128129.

SUMMARY OF THE INVENTION

However, it has been found that, with the liquid crystal display deviceconfigured having the protective cover affixed to the top surface of thepolarizing plate, it may happen that a place in which a bright spotdefect occurs comes out in a display of the liquid crystal displaydevice. Then, it has turned out that it is caused by a chemicalpolishing flaw, called a dimple, formed in a surface of an observer sidesubstrate of the liquid crystal display panel.

This kind of polishing flaw, when chemically polishing at least theobserver side substrate of the liquid crystal display panel, and formingit with a small thickness, being a flaw formed in a polished surfacethereof, the bright spot defect occurs due to an interface reflection inan interface with an air layer existing in the flaw. As heretoforedescribed, the polarizing plate is disposed, by means of the adhesive,on the polished surface of the substrate but, as an adhesive between thesubstrate and the polarizing plate normally has a small thickness of 10to 25 μm, the adhesive cannot completely fill the polishing flaw, and acondition is such that an air pocket still accumulates in the polishingflaw.

This leads to it being demanded that the bright spot defect caused bythe polishing flaw be avoided with a simple configuration, therebyachieving an improvement in a display quality.

Also, it has been found that, with the liquid crystal display deviceconfigured having the protective cover attached, it may happen that,other than the heretofore described dimple problem, a circular displayirregularity called a so-called yellow border occurs in which a displayarea of the liquid crystal display device turns yellow around aperimeter thereof.

It has turned out that this is due to the fact that, in the polarizingplate disposed on the observer side substrate of the liquid crystaldisplay panel to which is attached the protective cover, an edge likelyto absorb moisture expands, and the liquid crystal display panel isdeformed due to the expansion.

That is, the protective cover being configured of a relatively thickmaterial, the liquid crystal display panel affixed thereto experiences aforce in a direction opposite to the protective cover, on a perimeter ofthe liquid crystal display panel, due to the expansion of the edge ofthe polarizing plate, and is deformed in such a way as to have aconvexity on a protective cover side.

In the liquid crystal display panel, a portion in which a gap betweenthe pair of substrates widens appears in the display area of the liquidcrystal display panel due to this kind of deformation, and the yellowborder occurs in the portion.

This leads to it being demanded that the yellow border be avoided withthe simple configuration, thereby achieving the improvement in thedisplay quality.

An object of the invention is to provide a liquid crystal display devicein which it is possible, with a simple configuration, to avoid a brightspot defect caused by a chemical polishing flaw, called a dimple, whichis formed in a surface of an observer side substrate of a liquid crystaldisplay panel.

Another object of the invention is to provide a liquid crystal displaydevice in which it is possible, with a simple configuration, to avoid anoccurrence of a so-called yellow border.

In the previously mentioned JP-A-2001-42301, although there is nodisclosure of a problem caused by the yellow border, a liquid crystaldisplay device is disclosed in which, in the event that there is a flawin a substrate of a liquid crystal display panel, the flaw is filledwith a transparent resin layer, and a polarizing plate is attached to atop thereof by means of an adhesive layer. However, there is nodescription as to whether or not the flaw is caused by a chemicalpolishing, and a configuration is adopted such that no protective coveris provided.

Also, in the previously mentioned JP-A-4-326419, although there is nodisclosure of a problem caused by the dimple or the yellow border, adisclosure is included in which a touch panel (corresponding to theheretofore described protective cover) is disposed on an observer sidesurf ace of a liquid crystal display panel, but a configuration suchthat the touch panel is affixed to the liquid crystal display panel isnot adopted.

Also, in the previously mentioned JP-A-2006-221187, a liquid crystaldisplay device is disclosed in which a transparent touch switch isaffixed to a top of a polarizing plate, in the same way as inJP-A-2007-178758. However, the problem of the dimple is not disclosed.

Furthermore, in the previously mentioned JP-A-2007-128129, aconfiguration is disclosed such that a touch panel is affixed to aliquid crystal display panel by means of an adhesive 50, and apolarizing plate 6 a is disposed on a top surface of the touch panel.Also, a configuration is disclosed such that an upper substrate 8 a ofthe touch panel and a lower substrate 22 b of the liquid crystal displaypanel are made partially thin by means of a chemical polishing, and thepolarizing plate is disposed in this portion. However, there is nodescription of an upper substrate 22 a of the liquid crystal displaypanel being chemically polished, and no polarizing plate is affixed to abackside of the touch panel, either.

To briefly describe a summary of a typical invention, among inventionsdisclosed in the present application, it is as follows.

1. A liquid crystal display device according to the invention includes,for example,

a liquid crystal display panel having a first substrate, a secondsubstrate disposed on an observer side of the first substrate, and aliquid crystal layer sandwiched between the first substrate and thesecond substrate, and

a transparent cover affixed by means of a first bonding member to asurface of the liquid crystal display panel on the observer side,wherein

the transparent cover has an optical member affixed by means of a secondbonding member to a surface of the transparent cover facing the secondsubstrate,

the second substrate has a chemically polished surface on the observerside,

the first bonding member, as well as making direct contact with both thepolished surface of the second substrate and the optical member, coversall of a surface portion of the second substrate corresponding to adisplay area, and

the first bonding member is 30 to 200 μm in thickness, while the secondbonding member is 10 to 25 μm in thickness.

2. In the liquid crystal display device according to the invention, forexample, on the premise of the configuration 1, the first bonding memberis 30 to 100 μm in thickness.

3. In the liquid crystal display device according to the invention, forexample, on the premise of the configuration 1 or 2, the first bondingmember is an adhesive into which a liquid is cured.

4. In the liquid crystal display device according to the invention, forexample, on the premise of the configuration 1 or 2, the first bondingmember is an adhesive.

5. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 4, thesecond bonding member is an adhesive.

6. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 5, theoptical member includes at least one of a polarizing plate or aretardation plate.

7. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 6, whenviewed in plan, an edge of the transparent cover and an edge of theoptical member protrude outside the second substrate.

8. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 6, itfurther includes:

a seal material bonding the first substrate and the second substratetogether, wherein

when viewed in plan, an edge of the optical member is positioned on adisplay area side of the seal material, and

the first bonding member covers all of a side surface of the opticalmember.

9. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 6, itfurther includes:

a seal material bonding the first substrate and the second substratetogether, wherein

when viewed in plan, an edge of the optical member is superimposed onthe seal material.

10. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 9, thetransparent cover is a protective cover configured of a glass plate or aresin plate.

11. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 1 to 9, thetransparent cover has a function of a touch panel.

12. A liquid crystal display device according to the invention includes,for example,

a liquid crystal display panel having a first substrate, a secondsubstrate disposed on an observer side of the first substrate, and aliquid crystal layer sandwiched between the first substrate and thesecond substrate, and

a transparent cover affixed by means of a first bonding member to asurface of the liquid crystal display panel on the observer side,wherein

the transparent cover has an optical member affixed by means of a secondbonding member to a surface of the transparent cover facing the secondsubstrate, and

when viewed in plan, an edge of the transparent cover and an edge of theoptical member protrude outside the second substrate.

13. In the liquid crystal display device according to the invention, forexample, on the premise of the configuration 12, the second substratehas a chemically polished surface on the observer side,

the first bonding member, as well as making direct contact with both thepolished surface of the second substrate and the optical member, coversall of a surface portion of the second substrate corresponding to adisplay area, and

the first bonding member is 30 to 200 μm in thickness, while the secondbonding member is 10 to 25 μm in thickness.

14. In the liquid crystal display device according to the invention, forexample, on the premise of the configuration 12, the first bondingmember is 30 to 200 μm in thickness.

15. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 14, thefirst bonding member is 30 to 100 μm in thickness.

16. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 15, thefirst bonding member is an adhesive into which a liquid is cured.

17. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 15, thefirst bonding member is an adhesive.

18. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 17, thesecond bonding member is an adhesive having a thickness of 10 to 25 μm.

19. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 18, theoptical member includes at least one of a polarizing plate or aretardation plate.

20. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 19, thetransparent cover is a protective cover configured of a glass plate or aresin plate.

21. In the liquid crystal display device according to the invention, forexample, on the premise of any one of the configurations 12 to 19, thetransparent cover has a function of a touch panel.

The invention, not being limited to the above configurations, can bevariously modified without departing from the scope of the technicalidea of the invention.

With the liquid crystal display device configured in this way, it ispossible, with the simple configuration, to avoid the bright spot defectcaused by the chemical polishing flaw, called the dimple, which isformed in the surface of the observer side substrate of the liquidcrystal display panel. Also, with the liquid crystal display deviceconfigured in this way, it is possible, with the simple configuration,to avoid the occurrence of the so-called yellow border.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing one embodiment of a liquid crystaldisplay device according to the invention, corresponding to a sectiontaken along line I-I of FIG. 2;

FIG. 2 is an exploded perspective view showing one embodiment of theliquid crystal display device according to the invention;

FIG. 3 is a plan view showing one embodiment of a liquid crystal displaypanel used in the liquid crystal display device according to theinvention;

FIGS. 4A and 4B are sectional views showing another embodiment of theliquid crystal display device according to the invention, correspondingto a section taken along line I-I of FIG. 2;

FIGS. 5A to 5C are illustrations relating to a reason why a yellowborder occurs in a display area of the liquid crystal display panel;

FIG. 6 is an illustration showing a reason why it is possible to avoidthe yellow border in the liquid crystal display device according to theinvention; and

FIGS. 7A and 7B are sectional views showing still another embodiment ofthe liquid crystal display device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, a description will be given, using the drawings, ofembodiments of a liquid crystal display device according to theinvention.

Embodiment 1 Overall Configuration

FIG. 2, being an exploded perspective view showing one embodiment of theliquid crystal display device according to the invention, shows a liquidcrystal display device for a portable telephone.

Firstly, there is a liquid crystal display panel PNL. In the liquidcrystal display panel PNL, a substrate SUB1 and a substrate SUB2,disposed facing each other across a liquid crystal, being used as anenvelope, it is possible to recognize an image in a display area(indicated by a reference character AR in FIG. 3) of a substrate SUB2side surface. One side of the substrate SUB1 being formed extendedoutwardly of the substrate SUB2, a drive circuit DRV for independentlydriving each pixel in the display area is mounted on this extendedportion. Also, an external signal is input into the drive circuit DRVvia a flexible substrate FLB attached to the substrate SUB1.

Also, although not shown in the figure, a polarizing plate (indicated bya reference character POLL in FIG. 1) is affixed to a surface of thesubstrate SUB1 opposite to the liquid crystal. The polarizing plate POLLis provided in order to visualize a behavior of the liquid crystal.

Also, although a polarizing plate POL2 is also disposed on a surface ofthe substrate SUB2 opposite to the liquid crystal, the polarizing platePOL2, not being one directly attached to the substrate SUB2, isconfigured affixed to a side of a transparent cover COV, to be describedhereafter.

A more specific configuration of the liquid crystal display panel PNLwill be described hereafter using FIG. 3.

The transparent cover COV formed of, for example, a glass substrate (aglass plate) or a resin plate, which functions as, for example, aprotective cover, is disposed on a surface of the liquid crystal displaypanel PNL on an observer side.

In the transparent cover COV, a light blocking film BLK being formed inan area not including a portion of the liquid crystal display panel PNLfacing the display area AR, it is possible to recognize the display areaAR of the liquid crystal display panel PNL through a window WDsurrounded by the light blocking film BLK. The light blocking film BLKis formed on, for example, a bottom surface (a surface opposite to theobserver side) of the transparent cover COV by, for example, a printingor the like.

The polarizing plate POL2 is affixed to a surface of the transparentcover COV on a liquid crystal display panel PNL side. The polarizingplate POL2, having an adhesive (a bonding member) ADH2 formed in a sheetform, in advance, on one side thereof, can be affixed to the transparentcover COV by pressing the adhesive ADH2 against the transparent coverCOV. The adhesive ADH2, having a thickness of 10 to 25 μm, is of thesame kind as one used in a regular adhesive polarizing plate. However,to date, the polarizing plate POL2 has been affixed to the substrateSUB2 by means of the adhesive ADH2, while the embodiment has a featurein that it is affixed to the transparent cover COV side.

Also, in the transparent cover COV to which is affixed the polarizingplate POL2, the surface to which is affixed the polarizing plate POL2 isaffixed to a surface of the observer side substrate SUB2 of the liquidcrystal display panel PNL using, for example, a sheet form adhesive (abonding member) ADH1. That is, in the embodiment, a position of theadhesive ADH1 and a position of the adhesive ADH2 are inverted incomparison with heretofore known ones.

The adhesive ADH1, being formed larger in thickness than, for example,the adhesive ADH2 formed on the polarizing plate POL2, has a function offilling a chemical polishing flaw, called a dimple, formed in thesubstrate SUB2 of the liquid crystal display panel PNL, too, as will beapparent hereafter.

Furthermore, a backlight BL is disposed on a side of the liquid crystaldisplay panel PNL opposite to the transparent cover COV. The backlightBL is configured including a surface light source facing the displayarea AR of the liquid crystal display panel PNL.

In the heretofore described embodiment, the transparent cover COV hasbeen shown as one used as a protective cover but, this not beinglimiting, it is also acceptable that it is, for example, a substrateconfiguring a touch panel. That is, it is also acceptable that thetransparent cover COV is one having a function of a touch panel.

Also, in the heretofore described embodiment, the adhesive ADH1 used isone formed in a sheet form, but it is also acceptable that it is, forexample, an adhesive made of a liquid material. In this case, it issufficient that, for example, the adhesive made of the liquid materialis applied to a surface of the substrate SUB2 of the liquid crystaldisplay panel PNL (or a surface of the polarizing plate POL2 affixed tothe transparent cover COV), and the transparent cover COV to which thepolarizing plate POL2 is affixed in advance is bonded to it. In thiscase, by applying the adhesive ADH1 to the surface of the substrate SUB2of the liquid crystal display panel PNL in an amount such that theadhesive ADH1, when hardened, has a thickness of 30 to 200 μm (desirably30 μm to 100 μm), the adhesive ADH1 can reliably fill the chemicalpolishing flaw formed in the substrate SUB2.

Liquid Crystal Display Panel PNL

FIG. 3 is a schematic plan view showing one embodiment of the liquidcrystal display panel PNL shown in FIG. 2.

In FIG. 3, there being the substrate SUB1, the substrate SUB2 isdisposed, on a front side (the observer side), facing the substrateSUB1.

The substrate SUB2, being formed smaller in area than the substrateSUB1, has an area in which the substrate SUB1 is exposed, for example,on a bottom side in the figure. A drive circuit DRV, to be describedhereafter, formed of a semiconductor device, which independently driveseach pixel is mounted on the substrate SUB1 in this area.

The substrate SUB2 is fixed to the substrate SUB1 by a seal material SLwhich, being formed in a circular pattern, is disposed on a perimeter ofthe substrate SUB2, and the seal material SL seals in the liquid crystalsandwiched between the substrate SUB1 and the substrate SUB2.

A sealed in area of the liquid crystal surrounded by the seal materialSL configures the display area AR. The display area AR, to be exact,indicating an area (an area surrounded by the bold dashed line frame inthe figure) of an outer contour surrounding a collection of pixels, isused in this sense in the following description too. For this reason,there is a case of having a slight gap between the display area AR andthe seal material SL.

Gate signal lines GL, which extend in an x direction in the figure, andare provided in parallel in a y direction in the figure, and drainsignal lines DL, which are insulated from the gate signal lines GL,extend in the y direction in the figure, and are provided in parallel inthe x direction in the figure, are formed on a liquid crystal sidesurface of the substrate SUB1 in the display area AR.

An area surrounded by a pair of adjacent gate signal lines GL and a pairof adjacent drain signal lines DL (for example, an area indicated by adashed line frame B in the figure) configures a pixel area, by whichmeans pixel areas are disposed in a matrix form inside the display areaAR.

A thin film transistor TFT, which is activated in response to a signal(a scanning signal) from a gate signal line GL, a pixel electrode PX, towhich a signal (an image signal) from a drain signal line DL is suppliedthrough the activated thin film transistor TFT, and a capacitive elementCadd formed between another gate signal line GL, adjacent to the gatesignal line GL driving the thin film transistor TFT, and the pixelelectrode PX, are formed in each pixel area, as shown in a diagram B′ inwhich is enlarged the portion of the dashed line frame B in the figure,thereby configuring a pixel.

The capacitive element Cadd is provided in order to cause the imagesignal supplied to the pixel electrode PX to be stored for a long timein the pixel element PX.

Also, the pixel element PX causes an electric field to occur, betweenitself and an opposite electrode (not shown) formed in each pixel areain common, on a liquid crystal side surface of the substrate SUB2disposed facing the substrate SUB1.

A scanning signal is supplied to each gate signal line GL from the drivecircuit DRV via a wiring Wg which, being connected to a correspondingoutput terminal of the drive circuit DRV, is extended to one side ofleft and right sides of the liquid crystal display area AR. An imagesignal is supplied to each drain signal line DL from the drive circuitDRV via a wiring Wd from a corresponding output terminal thereof.

The scanning signal is sequentially supplied to each gate signal line GLin a way such as, for example, from an upper gate signal line to a lowerone, and furthermore, returning to the upper one, and the image signalis supplied in accordance with a timing of the supply of the scanningsignal.

An input signal is supplied to the drive circuit DRV via the flexiblesubstrate FLB fixed to an edge of the TFT substrate SUB1 on the bottomside in the figure.

Although not shown in the figure, a black matrix (a light blockingfilm), a color filter and the opposite electrode are formed on theliquid crystal side surface of the substrate SUB2, and an alignment filmis formed on a surface of the opposite electrode.

Also, although not shown in the figure, for example, spherical orcolumnar spacers are disposed, scattered between the substrate SUB1 andthe substrate SUB2, in an area surrounded by the seal material SL. Thisis for making a gap between the substrate SUB1 and the substrate SUB2uniform using the spacers.

FIG. 1, showing a view in a case in which the liquid crystal displaypanel PNL and the transparent cover COV are bonded together, shows asectional view taken along line I-I of FIG. 2 (an illustration of thelight blocking film BLK is omitted. The same applies in the followingsectional views).

The transparent cover COV, for example, being formed larger than theliquid crystal display panel PNL, is bonded in such a way that an outercontour of the liquid crystal display panel PNL is positioned inside anouter contour of the transparent cover COV.

The transparent cover COV has the polarizing plate POL2 affixed to asurface thereof on the liquid crystal display panel PNL side.

In the polarizing plate POL2, for example, an area thereof is formedsmaller than an area of the transparent cover COV, and an outer contourthereof is positioned inside the outer contour of the transparent coverCOV.

Then, the polarizing plate POL2 is formed in such a way that aperipheral edge thereof is superimposed on the seal material SL of theliquid crystal display panel PNL. As the polarizing plate POL2 has thefunction of visualizing the behavior of the liquid crystal in thedisplay area AR, this is for disposing the polarizing plate POL2,sufficiently covering at least the display area AR of the liquid crystaldisplay panel PNL.

The polarizing plate POL2, by attaching the sheet form adhesive ADH2,which is affixed to one surface thereof in advance, to the transparentcover COV, is affixed to the transparent cover COV, as heretoforedescribed. Herein, the adhesive ADH2, being relatively small inthickness, has a thickness of 10 to 25 μm.

Then, the transparent cover COV, to which the polarizing plate POL2 isaffixed in this way, is bonded to the liquid crystal display panel PNL,for example, with the adhesive ADH1, formed in the sheet form,interposed on a surface of the transparent cover COV on a polarizingplate POL2 side.

It is preferable that the adhesive ADHL has approximately the samerefractive index as, for example, the substrate SUB2 of the liquidcrystal display panel PNL (it is desirable that a refractive indexdifference between the two is 0.2 or less). This is for preventing anunnecessary interface reflection caused by a refractive index differencein an interface with the adhesive ADH1, avoiding a deterioration in adisplay contrast.

Also, the adhesive ADH1 has a thickness of 30 to 200 μm, which is largerthan the thickness of the adhesive ADH2 used in affixing the polarizingplate POL2 to the transparent cover cov.

With respect to the bonding of the transparent cover COV and the liquidcrystal display panel PNL, it is acceptable to either attach theadhesive ADH1 to the liquid crystal display panel PNL, and press thesurface of the transparent cover COV, on which is formed the polarizingplate POL2, against the adhesive ADH1, or to attach the adhesive ADH1 tothe surface of the transparent cover COV, on which is formed thepolarizing plate POL2, and press the liquid crystal display panel PNLagainst the adhesive ADH1. Also, it is also acceptable that the adhesiveADHL is any one of a so-called thermal curing type, a so-called lightcuring type, or a hybrid of the thermal curing type and the light curingtype.

The surface of the liquid crystal display panel PNL which is bonded tothe transparent cover COV being the surface of the substrate SUB2 on theobserver side, the adhesive ADH1 is directly attached to this surfaceover at least a whole of the display area AR. This is for avoiding adifference occurring in a light refractive index, in the display areaAR, depending on an existence or otherwise of the adhesive ADH1.

The observer side surface of the substrate SUB2 to which is attached theadhesive ADH1 is chemically polished over a whole area thereof.

This kind of polishing is performed in order to achieve a reduction inthickness of the substrate SUB1. As the polishing, it is also acceptableto adopt one which undergoes any one process of only a chemicalpolishing, a mechanical polishing after a chemical polishing, or achemical polishing after a mechanical polishing.

In this case, it may happen that, due to the heretofore describedchemical polishing, a chemical polishing flaw DNP called a so-calleddimple is occurring on the observer side surface of the substrate SUB2.The chemical polishing flaw DNP is filled with the adhesive ADH1,avoiding an accumulation of air in the chemical polishing flaw DNP. Thisis because the adhesive ADH1, being 30 to 200 m in thickness, asheretofore described, has a thickness sufficient to fill the chemicalpolishing flaw DNP.

A view inside the solid line circle A′ in the figure is a view showingin enlarged dimension an interface portion (a portion of a dashed linecircle A) between the substrate SUB2 and the polarizing plate POL2. Asshown in the same view, it can be seen that a polishing flaw DNP calleda dimple is formed in the surface of the substrate SUB2, and thepolishing flaw DNP is sufficiently filled with the adhesive ADH1 formedbetween the substrate SUB2 and the polarizing plate POL2.

By this means, it is possible to avoid a bright spot defect occurringdue to air accumulated in the polishing flaw DNP in the surface of thesubstrate SUB2.

Incidentally, in a case in which, as heretofore known, the polarizingplate POL2 is fixed to the liquid crystal display panel PNL, using theadhesive ADH2 adhering to the polarizing plate POL2, and a bonding ofthe polarizing plate POL2 of the liquid crystal display panel PNL andthe transparent cover COV is carried out using an adhesive equivalent tothe adhesive ADH1, that is, in a case in which the adhesive ADH1 and theadhesive ADH2 are positioned in inverse relation to that of theembodiment, a thickness of the adhesive ADH2 being small, a case occursin which the polishing flaw DNP formed in the substrate SUB2 is notsufficiently filled with the adhesive ADH2, causing a problem in that itis not possible to adopt a sufficient countermeasure against theso-called bright spot defect.

As the adhesive ADH1 is also formed in order to solve the problem causedby the polishing flaw DNP formed in the display area AR of the substrateSUB2, it is necessary that it is formed in such a way as to cover thedisplay area AR. However, it is also acceptable that the adhesive ADH1is formed beyond the display area AR. In other words, it is alsoacceptable that a peripheral edge of the adhesive ADH1 is formed, forexample, as far as an outer area of the seal material SL, as shown inFIG. 1.

Embodiment 2

FIG. 4A, being a configuration view showing another embodiment of theliquid crystal display device according to the invention, is drawncorresponding to FIG. 1. In FIG. 4A, members with reference charactersidentical to those of FIG. 1 are identical to the members shown in FIG.1.

Firstly, in FIG. 4A, a configuration which is distinctive in comparisonwith FIG. 1 is that a transparent cover COV, being formed larger than aliquid crystal display panel PNL, is bonded in such a way that an outercontour of the liquid crystal display panel PNL is positioned inside anouter contour of the transparent cover COV.

Then, another distinctive configuration is that a polarizing plate POL2too, being formed larger than the liquid crystal display panel PNL, isof a size such that the outer contour of the liquid crystal displaypanel PNL is positioned inside an outer contour of the polarizing platePOL2. The polarizing plate POL2 is fixed over a whole area, orapproximately the whole area, of a surface of the transparent cover COVon a liquid crystal display panel PNL side, using an adhesive ADH2interposed between the polarizing plate POL2 and the transparent coverCOV.

In other words, the distinctive configuration lies in that, when viewedin plan, an edge of the transparent cover COV and an edge of thepolarizing plate POL2 are configured in such a way as to protrudeoutside a substrate SUB2 of the liquid crystal display panel PLN.

By configuring in this way, it is possible to obtain a liquid crystaldisplay device for which a countermeasure is taken against a so-calledyellow border. A detailed description of the yellow border and thecountermeasure against it will be given hereafter.

In the liquid crystal display device shown in the embodiment, in a caseof attempting to take only the heretofore described countermeasureagainst the yellow border, it is also acceptable that, for example, asshown in FIG. 4B, the polarizing plate POL2 is fixed to the liquidcrystal display panel PNL, using the adhesive ADH2 (thickness: 10 to 25μm) adhering to the polarizing plate POL2 in advance, and a bonding ofthe liquid crystal display panel PNL and the transparent cover COV iscarried out using the same kind of adhesive ADH1 (thickness: 30 to 200μm) as the adhesive ADH1 shown in the embodiment 1. In this case, it isdesirable that a surface of the substrate SUB2 is not chemicallypolished.

However, in the event that, as shown in FIG. 4A, the polarizing platePOL2 is fixed to the transparent cover COV, using the adhesive ADH2adhering to the polarizing plate POL2, and the bonding of the liquidcrystal display panel PNL and the transparent cover COV is carried outusing the ADH1, an advantageous effect is achieved in that it ispossible to adopt the countermeasure against the yellow border, as wellas the same kind of countermeasure against the dimple as that shown inthe embodiment 1.

Herein, a description will be given, using FIGS. 5A to 5C, of a reasonwhy the yellow border occurs in a case in which, unlike the heretoforedescribed configuration of the embodiment 2, an edge of a transparentcover COV and an edge of a polarizing plate POL2, when viewed in plan,being inside a substrate SUB2 of a liquid crystal display panel PNL, areconfigured not protruding outside the substrate SUB2 of the liquidcrystal display panel PNL.

FIG. 5A is a view showing a case in which the edge of the transparentcover COV bonded to the liquid crystal display panel PNL, and the edgeof the polarizing plate POL2 interposed between the liquid crystaldisplay panel PNL and the transparent cover COV, are inside the liquidcrystal display panel PNL. In order to simplify a description, a drawingof an adhesive formed between the polarizing plate POL2 and thetransparent cover COV, and an adhesive between the polarizing plate POL2and the liquid crystal display panel PNL, is omitted.

FIG. 5B shows that the polarizing plate POL2 absorbs moisture at theedge thereof, and the edge expands. This expansion reaches to an areaoverlapping the transparent cover COV. In this case, a deformation ofthe transparent cover COV due to the expansion of the edge of thepolarizing plate POL2 is slight. This is because it is common that thetransparent cover COV is formed thicker than a substrate SUB1, and thesubstrate SUB2, of the liquid crystal display panel PNL.

Meanwhile, the liquid crystal display panel PNL is deformed (curved) insuch a way as to have a convexity on a transparent cover COV side. Thisis because, in the liquid crystal display panel PNL attached to thetransparent cover COV, a perimeter thereof experiences a force in adirection opposite to the transparent cover COV side due to theexpansion of the polarizing plate POL2.

The heretofore described deformation of the liquid crystal display panelPNL is also undergone in the same way, as well as in the substrate SUB2attached to the transparent cover COV side, in the substrate SUB1 fixedby the substrate SUB2 and a seal material SL.

In this case, as spacers exist in a space in which is sealed a liquidcrystal between the substrate SUB1 and the substrate SUB2, as heretoforedescribed, it does not happen that a gap between the substrate SUB1 andthe substrate SUB2 becomes smaller (a portion of a gap α in the figure)over approximately a whole of a display area AR, but a phenomenon occursin which a distortion occurs in a portion spaced apart and slightlyinward from the seal material SL, and the gap becomes larger (a portionof a gap β in the figure) in the portion. For this reason, a thicknessof a liquid crystal layer changes in the portion.

Then, in the portion, as shown in FIG. 5C which is a schematic plan viewof the liquid crystal display panel PNL, a circular yellow border YBoccurs in a vicinity of the seal material SL inside the display area ARof the liquid crystal display panel PNL.

As opposed to this, FIG. 6, being a simple configuration view of theembodiment, drawn corresponding to the heretofore described FIG. 4A,shows that an expansion (indicated by an arrow SW in the figure) occursat an edge of a polarizing plate POL2.

However, as heretofore described, an edge of a transparent cover COV andthe edge of the polarizing plate POL2 being configured protrudingoutside a substrate SUB2 of a liquid crystal display panel PNL, aconfiguration is such that the heretofore described expansion of thepolarizing plate POL2 does not affect the liquid crystal display panelPNL, that is, it does not exert a force on a liquid crystal displaypanel PNL side.

For this reason, it not happening that a deformation occurs in theliquid crystal display panel PNL due to the expansion of the polarizingplate POL2, it is therefore possible to avoid the occurrence of theyellow border.

Also, it is desirable that an area in which the polarizing plate POL2expands does not overlap the substrate SUB2 but, even though there issome overlap, as the edge of the polarizing plate POL2 is in a positionfurther from a display area AR in comparison with the embodiment 1, evenin the event that the liquid crystal display panel PNL is somewhatdeformed, as a portion in which a gap of a liquid crystal layer changesis outside the display area AR, it is possible to avoid effects of theyellow border.

With respect to this kind of yellow border, in a case in which thetransparent cover COV is configured of, for example, an acrylic resin,as the edge thereof is likely to expand in the same way as thepolarizing plate POL2, in this kind of case too, it is preferable toapply the invention.

Embodiment 3

FIG. 7A, being a sectional view showing still another embodiment of theliquid crystal display device according to the invention, is acorresponding view of FIG. 1. In FIG. 7A, members with referencecharacters identical to those of FIG. 1 are identical to the membersshown in FIG. 1.

In FIG. 7A, in a case of comparing with the configuration of FIG. 1, ina polarizing plate POL2 affixed to a transparent cover COV by means ofan adhesive ADH2, an edge thereof, as well as the adhesive ADH2, ispositioned inside an area surrounded by a seal material SL spaced, forexample, a distance a (0.2 mm or less) away from a center of the sealmaterial SL.

Also, an adhesive ADH1 which bonds together the transparent cover COV,to which is affixed the polarizing plate POL2, and a liquid crystaldisplay panel PNL is formed in a condition in which it completely coversthe polarizing plate POL2, and an edge of the adhesive ADH1 ispositioned outside an area surrounded by the seal material SL, forexample, spaced a distance β (0.1 mm or less) away from the center ofthe seal material SL.

It goes without saying that the polarizing plate POL2 covers theheretofore described display area AR of the liquid crystal display panelPNL. This is because the polarizing plate POL2 is provided in order tovisualize the behavior of the liquid crystal in the display area AR.

With the liquid crystal display device of the heretofore describedconfiguration, as all of the edge (a side surface) of the polarizingplate POL2 is covered with the adhesive ADH1, it not happening thatmoisture is absorbed from the edge of the polarizing plate POL2, it ispossible to avoid an expansion of the edge. Consequently, it is possibleto prevent the occurrence of the yellow border.

Also, by setting each of the edge of the polarizing plate POL2 and theedge of the adhesive ADH1 in a position within the heretofore describedrange from the center of the seal material SL, it being possible tosecure a large distance from the edge of the polarizing plate POL2 tothe edge of the adhesive ADH1, it is possible to reliably prevent apenetration of moisture into the edge of the polarizing plate POL2.

However, this not being limiting, as shown in FIG. 7B, it is alsoacceptable that the polarizing plate POL2, as well as the adhesive ADH2,is extended outward in such a way that the edges thereof aresuperimposed on the seal material SL, or aligned with the center of theseal material SL.

In the embodiment 3, a description has been given mainly of aconfiguration for the countermeasure against the yellow border. However,it goes without saying that, in the same way as in the embodiment 1, aconfiguration is adopted such that, in a case in which a substrate SUB2of the liquid crystal display panel PNL is chemically polished, it ispossible to avoid the yellow border along with an adverse effect causedby the chemical polishing flaw DNP called the dimple. This is because aconfiguration is adopted such that a surface of the substrate SUB2 iscovered with the adhesive ADH1 which is large in thickness, in thedisplay area AR of the surface.

In the heretofore described embodiments 1 to 3, the polarizing platePOL2 is taken as one example of an optical member adhering to thetransparent cover COV. However, this not being limiting, needless tosay, it is acceptable that it is another optical member such as, forexample, a retardation plate. That is, it is sufficient that the opticalmember includes at least one of the polarizing plate or the retardationplate.

It is also acceptable to employ the heretofore described embodiments 1to 3 individually, or in combination unless they are mutually exclusive.This is because the advantages in each embodiment can be achievedindividually or synergetically.

1. A liquid crystal display device comprising: a liquid crystal displaypanel having a first substrate, a second substrate disposed on anobserver side of the first substrate, and a liquid crystal layersandwiched between the first substrate and the second substrate, and atransparent cover affixed by means of a first bonding member to asurface of the liquid crystal display panel on the observer side,wherein the transparent cover has an optical member affixed by means ofa second bonding member to a surface of the transparent cover facing thesecond substrate, the second substrate has a chemically polished surfaceon the observer side, the first bonding member, as well as making directcontact with both the polished surface of the second substrate and theoptical member, covers all of a surface portion of the second substratecorresponding to a display area, and the first bonding member is 30 to200 μm in thickness, while the second bonding member is 10 to 25 μm inthickness.
 2. The liquid crystal display device according to claim 1,wherein the first bonding member is 30 to 100 μm in thickness.
 3. Theliquid crystal display device according to claim 1, wherein the firstbonding member is an adhesive into which a liquid is cured.
 4. Theliquid crystal display device according to claim 1, wherein the firstbonding member is an adhesive.
 5. The liquid crystal display deviceaccording to claim 1, wherein the second bonding member is an adhesive.6. The liquid crystal display device according to claim 1, wherein theoptical member includes at least one of a polarizing plate or aretardation plate.
 7. The liquid crystal display device according toclaim 1, wherein when viewed in plan, an edge of the transparent coverand an edge of the optical member protrude outside the second substrate.8. The liquid crystal display device according to claim 1, furthercomprising: a seal material bonding the first substrate and the secondsubstrate together, wherein when viewed in plan, an edge of the opticalmember is positioned on a display area side of the seal material, andthe first bonding member covers all of a side surface of the opticalmember.
 9. The liquid crystal display device according to claim 1,further comprising: a seal material bonding the first substrate and thesecond substrate together, wherein when viewed in plan, an edge of theoptical member is superimposed on the seal material.
 10. The liquidcrystal display device according to claim 1, wherein the transparentcover is a protective cover configured of a glass plate or a resinplate.
 11. The liquid crystal display device according to claim 1,wherein the transparent cover has a function of a touch panel.
 12. Aliquid crystal display device comprising: a liquid crystal display panelhaving a first substrate, a second substrate disposed on an observerside of the first substrate, and a liquid crystal layer sandwichedbetween the first substrate and the second substrate, and a transparentcover affixed by means of a first bonding member to a surface of theliquid crystal display panel on the observer side, wherein thetransparent cover has an optical member affixed by means of a secondbonding member to a surface of the transparent cover facing the secondsubstrate, and when viewed in plan, an edge of the transparent cover andan edge of the optical member protrude outside the second substrate. 13.The liquid crystal display device according to claim 12, wherein thesecond substrate has a chemically polished surface on the observer side,the first bonding member, as well as making direct contact with both thepolished surface of the second substrate and the optical member, coversall of a surface portion of the second substrate corresponding to adisplay area, and the first bonding member is 30 to 200 μm in thickness,while the second bonding member is 10 to 25 μm in thickness.
 14. Theliquid crystal display device according to claim 12, wherein the firstbonding member is 30 to 200 μm in thickness.
 15. The liquid crystaldisplay device according to claim 12, wherein the first bonding memberis 30 to 100 μm in thickness.
 16. The liquid crystal display deviceaccording to claim 12, wherein the first bonding member is an adhesiveinto which a liquid is cured.
 17. The liquid crystal display deviceaccording to claim 12, wherein the first bonding member is an adhesive.18. The liquid crystal display device according to claim 12, wherein thesecond bonding member is an adhesive having a thickness of 10 to 25 μm.19. The liquid crystal display device according to claim 12, wherein theoptical member includes at least one of a polarizing plate or aretardation plate.
 20. The liquid crystal display device according toclaim 12, wherein the transparent cover is a protective cover configuredof a glass plate or a resin plate.
 21. The liquid crystal display deviceaccording to claim 12, wherein the transparent cover has a function of atouch panel.